The invention relates to an electromagnetic system for actuating the blades or slides in the shutters of photographic devices, particularly in photographic cameras.
In the field of photographic cameras it is well known to operate the shutter blades by means of one or more electromagnets. The blade actuation may be accomplished in such a manner that the blades are actually driven by the electromagnet, or the shutter construction may be such that the electromagnet is only used for retaining the shutter blades in the shutter open position while spring means are provided which close the shutter when the electromagnet releases the blades at the end of the exposure time upon reception of a pulse from a time control member (RC-circuit).
In such shutters the reaction time of the electromagnet is of decisive importance for an exact exposure time. If, for example, the electromagnet has a reaction time of 2 msec it will be difficult to achieve an exposure time shorter that 1/500 sec. The mentioned reaction time of 2 msec is in fact already a very short time interval. Therefore, substantially shorter exposure times cannot be achieved with the electromagnetic drive systems so far known in the art.
It is, therefore, an object of the invention to provide an electromagnetic drive system for photographic shutters by which very much shorter exposure times, e.g. 1/2 msec=1/2000 sec and even shorter may readily be obtained.